Polymerization and condensation products



Patented Apr. 22, 1941 I UNITED STATES 2,239,534 I POLYMERIZATION AND CONDENSATION raonoors Louis A. Mikeska, Westfleld, N. 1., and Eugene Lleber, West New Brighton, Staten Island, N. Y., asslgnors to Standard Oil Development Oompany,acorporation of Delaware No Drawing. Application September 2, 1939, a

Serial No. 293,304 i 16 Claims. (Cl. 260-6) This invention relates to improved polymerization and condensation products of phenol sulfides which are suitable for use as oxidation inhibitors in .mineral oil compositions, particularly to improve the stability of mineral oils when exposed 'to elevated temperatures such as when they are used as lubricants in internal combustion engines. In a copending application. Serial No. 51,827,

filed November 27, 1935, by Louis A. Mikeska and Charles A. Cohen (now Patent No. 2,139,766), there is described the use of certain substituted aryl thioethers as stabilizing agents for mineral oils. In a second copending application Serial No. 93,764, filed August 1, 1936, by the present inventors, there is described the use of a class of substituted aryl polysulfides for the same pur pose. It has also been discovered that higher reaction products which are solublein hydrocarbon oils, particularly the dimers and trimers of these vtwo classes of organic sulfur compounds, may be prepared and that they also possess many desirable characteristics particularly as mineral oil stabilizing agents. This application is filed in order to present claims to such products and their preparation. It is a continuation-in-part of our copending application Serial No. 97 197, filed August 21, 1936, now Pat. No. 2,198,828 which contains claims to lubricating compositions con,- taining the compounds described herein.

The compounds of the present invention are represented by the following formula:

where R is an alkyl group containing at least 4 carbon atoms. Compounds containing 2 alkyl phenol groups in which the alkyl radicals contain at least 4 carbon atoms are preferred. The alkyl groups may be normal, iso, secondary or tertiary. They may also be cyclo aliphatic, but the open chain groups are preferred. R and R" are pref- 'erably the same as R, but may also be any other and is preferably 2 or 4; n and n represent integers from 1 to 4 and are preferably 1 or 2, and 11. may represent different integers in different groups of the same molecule when u is-greater than 1. The linkage between the aromatic nuclei is preferably through the sulfur atoms. The benzene ring also represents linked aromatic rings such as diphenyl and condensed aromatic rings such as naphthyl.

The compounds of this invention also include derivatives of the alkyl phenol sulfides which contain other substituent groups in addition to the hydroxy and alkyl groups. substituent groups should not, however, offset the solubilizing effect of the alkyl groups to an extent suflicient to render the compound insoluble in lubricating oils. Examples of suitable groups or radicals, which may be attached to either the aryl or the alkyl group, are alkyl and aryl hydrocarbon radicals, also such radicals containingoxygen in the form of ether, aldehyde,

ketone, acid or ester groups, those containing nitrogen in the form of amine or nitrile groups and those containing sulfur, selenium, tellurium and the like.

The sulfur atoms linking the organic groups of the alkyl phenol sulfides may be wholly or partly replaced by the heavier non-metallic elements of group 6 of the periodic table, such as selenium and tellurium.

Preferred examples of this class of compounds are indicated by the followingformulae, together with suitable methods for the preparation of these classes of compounds. In each of these formulae, R represents an alkyl radical having at least 4, and preferably from 4 to 8 carbon atoms.

- r r I I on on on on The above formulae are diagrammatic and the hydroxyl and alkyl radicals are not limited to the Such additional positions shown there in Each of these radicals may be connected to any position in the benzene ring, but those compounds in which the alkyl radicals are in ortho or para position to the hydroxyl group are preferred.

While these compounds may be added in any desired concentration within their solubility limits to lubricating oils, they are preferably used in concentrations of about 0.1 to 2.0% and a concentration of about 0.5% will be found suflicient to stabilize the majority of petroleum lubricating oils. Larger proportions, that is up to about 5% or more, may be used to improve the lubricating properties of the oil. These compounds may be prepared by various methods.

' prepared by reacting butyl phenol with sulfur dichloride. The reaction is preferably conducted in the presence of an inert solvent, preferably an alkyl halide suchas ethylene chloride, at a temperature of about 60to 140 C., preferably about.

80 to 110C. The solvent preferably boils at the reaction temperature and the reaction is conducted under reflux until the hydrogen chloride formed thereby is' completely eliminated. This process is described in the copending application Serial No. 93,764 of Mikeska and Lieber, referred to above. A polymer product of superior quality is obtained by bringing the sulfur dichloride slowly into contact with the phenol solution at a temperature of about 30 to 40 C., maintaining this temperature by cooling until all reagents have been added, then heating the mixture to the boiling point of the solvent and refluxing it for about two hours. In this manner the possibility of reversion of the sulfur dichloride to sulfur monochloride is avoided and the polymer product, in concentrated form, is less corrosive to copper in the copper strip test.

A second and preferred method for preparing polymers of this type is to bring a dialkyl diphenol sulfide into reaction with sulfur dichloride, using about 2 mols of the former per mol of sulfur dichloride. For example, the dimers of tertiary amyl phenol thioether may be prepared by bringing the tertiary amyl phenol thioether into reaction with sulfur dichloride in the manner described. This reaction may be conducted in the same solvents and with the same operating con.

ditions described above. In this way a substanmolecules may be prepared by bringing a Ibutyl phenol thioether into reaction with sulfur monochloride in the manner described.

Compounds of Class III may be prepared by bringing an alkyl phenol intoreaction with a slight excess of sulfur monochloride, using between about 0.5 and 0.75, preferably between 0.6 and 0.7, mols of sulfur monochloride per mol of the alkyl phenol. By this means both the alkyl phenol disulfide and polymers thereof are formed. The polymers may be separated from the monomer by extraction with selective solvents, or by other suitable means. Such polymers may also be prepared by bringing a dialkyl diphenol disulfide into reaction with sulfur monochloride, using about 2 mols of the former per mol of sulfur monochloride. These reactions may be conducted in the same solvents and under the same operating conditions described above. For example, the dimer andtrimer of ditertiary amyl diphenol disulfide, in which the monomer portions of their molecules are linked by a disulfide group, may be prepared by bringing ditertiary amyl diphenol disulfide into reaction with sulfur monochloride in the manner described.

Compounds of Class IV may be prepared by bringing a diallcvl diphenol disulfide into reaction with sulfur dichloride in the samesolvents and under the same operating conditions described above, using preferably about 2 mols of the, dialkyl diphenol disulfide per mol of sulfur dichloride. For example, the dimer of dibutyl diphenol disulfide, in which the monomer portions of its.

molecules are connected by thioether linkages, may be prepared by bringing dibutyl diphenol disulfide into reaction with sulfur dichloride in the manner described.

Compounds of Class V may be prepared by bringing a dialkyl diphenol tetrasulfide into reaction with sulfur monochloride, using preferably about 2 mols of tetrasulfide per mol of sulfur monochloride. For example, the dimer of diamyl diphenol tetrasulfide in which the monomer portions of its molecules are joined by disulfide linkages, may be prepared by bringing the diamyl diphenol tetrasulfide into reaction 'with sulfur monochloride in the manner described.

All of the above preparations may be conducted in the solvents and under the operating conditions described in connection with the preparation of compounds of Class I.

Higher polymers'may be obtained by using slightly higher ratios of the sulfur chloride re-' agent to the phenol or by bringing any'of the polymers above described into further reaction with sulfur dichloride or sulfur monochloride under the same conditions already described.

The following example is presented to illustrate one process for preparing the compounds of this invention.

Example 1 125 grams of ditertiary amyl diphenol sulfide (2 molar proportions) were dissolved in 500 cc. of ethylene chloride and the solution was heated to boiling under reflux. 18 grams (one molar proportion) of sulfur dichloride were dissolved in cc. of ethylene chloride. This solution was added with stirring to the boiling solution of the amyl phenol sulfide. The hydrogen chloride gas evolved during the reaction was withdrawn from the reaction zone through the reflux condenser. When the addition of the sulfur dichloride solution was completed, the refluxing of the reaction mixture was continued for six hours when no further evolution of hydrogen chloride took place. By this means, all hydrogen chloride is removed and there is no need to wash the reaction product with water. The time of refluxing can be cut arsenal down by blowing an inert gas such as nitrogen or flue gas through the reaction mixture.

The solvent, ethylene chloride, was then re-' moved from, the reaction mixture by distiliation, and the product was then distilled under vacuum.

7 The head temperature in the vacuum ltill was oils and lubricating oils, and in many other orvganic solvents.

The compounds described above may be used as oxidation inhibitors and improving agents in similar concentrations in other hydrocarbons and hydrocarbon compositions such as waxes, lubricating oils, greases, asphalts, fuel oils, Diesel oils, naphthas, burning oil, gasoline, andthe like.

These compounds may also be used as oxidation inhibitors generally in organic materials The hydroxyl groups of the phenol sulfide polymers may be partially or completely esterifled with organic acids, preferably fatty acids. The

which are subject to degradation by oxidation during. normal conditions of storage or use, or which tend to deteriorate by absorption of oxygen from the air. Examples of such materials are: fatty oils and waxes, petroleum oils and their derivatives, soaps, aldehydes, synthetic resins, rubber, synthetic rubber, paper and the like. Thus, these compounds can beused to protect waxes from becoming rancid, especially the waxes of the type used to line food and beverage containers.

The compounds of. this invention greatly stabilize mineral lubrlcatingoils at elevated temperatures, especially the highly refined oils such assynthetic oils, solvent extracted oils obtained by treatment of minerailubricating oils with single solvents such as phenol, dichlorethyl ether,furfural, propane, nitrobenzene, crotonaldehyde,

etc., or by double ormultiple solvents such as,

propane-cresol, etc., clay or acid treated oils, also aluminum chloride treated oils, white oils, hydrogenated oils, and the like. These compounds are 7 especially effective with such oils having viscosity indices above 60 to 80. Lubricating oils which also may be stabilized by these compounds are mineral oils of over 35 or 40 Saybolt viscosity at 210 F., and even those having a viscosity of over 100 seconds at'100 F., which are either in the crude form or have been partially or highly refined by distillation, voltolization, chemical reagents, or adsorptive agents; as well as coal tar or shale distillates, pale oils, neutrals, bright stocks and other residual stocks, cracking coil tar fractions, condensed or polymerized fractions,

and the like, which may beeither waxy, dewaxed, ornon-wan. Q

The lubricants to which these stabilizing agents are added may also contain dyes, metallic or other soa'ps,,pour inhibitors, sludge dispersers, oxidation inhibitors, thickeners, V. I. improvers such as soluble linear polymers, oiliness agents, resins, rubber, fatty oils, heat thickened fatty oils, sulfurized fatty oils, extreme pressure lubricating agents, organo-metal'li'c compounds, bright stocks such as refined petroleum lubricating oil residues,

voltolized fatty oils, mineral oils or waxes, colloidal solids such asgraphite, zinc oxide, etc., and the like..

resulting esterified compounds are particularly effective as oiliness agents in lubricating oils. These esterifled compounds may bemixed and used with non-esterined alkyl phenol sulfide polymers. These oiliness agents may be used in any suitable concentration. The amount used is usually between 0:1 and 5.0% of the total composition, and 0.5 to 2.0% is generally sufilcient. I The following examples illustrate the use of the compounds described herein as stabilizing agents in lubricating oils.

: Egrample 2 0.2% of the dimer of ditertiary amyl diphenol sulfide, a Class I compound,.was blended with; an S. A. E. 20 lubricating oil derived from petroleum. A blend of the same concentration of ditertiary arnyl diphenol sulfide was also prepared with a sample of.the same oil. Corrosive action, Slig'h numbers and cone numbers were. determined for the original oil and the blends,with the following results.

Blends Original oil Dlgi yl dip ol Polymer w ilde Corrosion Passes Passes Passes SlighNo 23.8 21.4 0.8 ConeNo 0.45 0.14 0.11

It will be noted that the polymer reduced not only the cone number even more than did the .diamyl diphenol sulflide, but it also reduced the Sligh number to such an extent that sludge formation was almost inappreciable, while the diamyl diphenol sulfide had very little effect on the Sligh number. r

A description of the methods of testing in the above example are as follows:

Corrosion test.This consists in immersing a used bright copper strip for three hours in the oil tion of this test, the oxidation is continued for 24 hours. r Cone test-This test is a means for determining the tendency of an oil to deposit solid matter upon heated metallic surfaces. It consists in slowly drop i the oil to be tested onto va heated metal (generally steel) cone, having .a cireumferential groove milled out in a screw fashion on the periphery so as'to allow a timeofc ohtact of about one minute between theheated'steel surface and the oil. A total volume of .60 caof oil is dropped from a dropping funnel. onto the cone over a period of 2 hours; Thetemperature of the cone may be any desired value, but for lubricating oils 250 C. is preferable since it ap proximately represents the extreme temperature to which oils are expo ed in ordinary engine use. The cone is weighed before the test. After all of the oil is run over the metal surface. the cone is washed with naphtha to remove adhering oil and is then weighed, the weight of the solid deposit being equal to the difference in weight 'of the cone before and after the test. This value p is generally reported in grams.

Example 3 Runs were made in a C. F. R. (Cooperative Fuel Research) engine under closely comparable conditions using a highly refined petroleum lubricating oil of '72 seconds Saybolt viscosity .at 210 F.- and blends of 0.2% of ditertiary amyl diphenol sulfide (A) and of the dimer thereof (B), prepared as in Example 1, in separate portions of the same oil. After each run the engine was taken down, inspected and rated by demerits according to the condition of the piston parts, valves and cylinder. On this scale, the demerit rating is higher as the engine condition is worse. The runs were each madefor 14 hours at a jacket temper- .ature of 375 F. The results are given below:

C. If. R, engine tests A Blends Blank Demerit 5.2 2.3 l.9

3. Polymerization and condensation products of alkyl phenol sulfides having the following formula:

a n R a l I I $11 11 on on where R represents alkyl groups of 4 to 8 carbon atoms.

4. Polymerization and condensation products of alkyl phenol sulfides having the following formula:

i i" r i i s we where R represents alkyl groups of 4 to 8 carbon atoms.

5. Polymerization and condensation products of alkyl phenol sulfides having the following formula:

R R R R on on on on where R represents alkyl groups of 4 to 8 carbon atoms. 1

6. The dimer of a dialkyl diphenol thioether, having a sulfur linkage between the monomeric portions of its molecule.

7. The dimer of a dialkyl diphenol disulfide,

' having a sulfur linkage between the monomeric 1. Polymerization and condensationproducts of phenol sulfides, having the following formula:

where R is an alkyl group of at least 4 carbon atoms, R and R" are selected from the class consisting of alkyl groups and hydrogen, n and n are integers from 1 to 4 and 1 is an integer from 2. Polymerization and condensation products of alkyl phenol sulfides, having the following formula:

where R, R and R" are allwl groups of 4 to 8 carbon atoms each, and n are integers from 1 to 2, and '1: is an integer from 2 to 4.

'portions of its molecule;

8. The dimer of ditertiary amyl diphenol thioether, having a sulfur linkage between the monomeric portions of its molecule.

9. The dimer of ditertiary amyl diphenol disulfide, having a sulfur linkage between the monomeric portions of its molecule.

10. A polymer of a dialkyl diphenol sulfide,

, prepared'by condensation of said dialkyl diphenol sulfide with a sulfur chloride, said alkyl groups having from 4 to 8 carbon atoms each and said polymer being a viscous liquid which is soluble in hydrocarbon oils and which is unvaporized at 250 C. at a pressure of 3 mm. of mercury.

11. A polymer according to claim 10 in which said polymer is a product of the condensation of ditertiary amyl diphenol thioether and sulfur dichloride.

12. Process for preparing polymers of alkyl .phenol sulfides comprising bringing an alkyl phenol sulfide having at least 4 carbon atoms in the alkyl group into reaction with a sulfur halide.

13. Process according to claim 12 in which said alkyl group has from 4 to 8 carbon atoms.

14. Process according to claim 12 in which said alkyl phenol sulfide is a thioether.

15. Process according to claim 12 in which said alkyl phenol sulfide is a disulfide.

16. Process according to claim 12 in which said sulfur halide is sulfur monochloride.

LOUIS A. MIKESKA. EUGENE LIEBER. 

